Neutralizing bath for use in photographic processing

ABSTRACT

A neutralizing bath, employed in processing photographic elements to neutralize residual aldehyde resulting from prior treatment in an aldehydic prehardening bath and thereby to avoid the deleterious effects of carry through of the aldehyde into subsequent processing baths, is comprised of hydroxylamine or a water-soluble acid addition salt thereof and an hydroxyalkylidene diphosphonic acid or water-soluble salt thereof. The hydroxylamine serves to neutralize the aldehyde by reacting therewith, while the hydroxyalkylidene diphosphonic acid serves to stabilize the bath and facilitate its long term storage by inhibiting decomposition of the hydroxylamine.

United States Patent Malloy Mar. 7, 1972 PHOTOGRAPHICPROCESSING [72] Inventor: Richard J. Malloy, Rochester, NY. [73] Assignee: Eastman Kodak Company, Rochester,

[22] Filed: June 8, 1970 [21] Appl. No.: 44,576

[51] Int. Cl ..G03c 5/26 [58] Field of Search ..96/48 QP, 50 PT, 50, 66.4, 96/66; 252/188, 389

[56] References Cited UNITED STATES PATENTS 3,141,771 7/1964 Bard 96/664 3,l68,400 2/ 1965 Blackmer. ..96/22 3,201,246 8/1965 Allen ...96/66.4

3,214,454 10/1965 Blaser ..252/ 180 3,431,217 3/1969 Hwa ..252/389 3,488,707 l/i970 Willems ...,.96/67 3,502,577 3/ 1970 Hutchins ..96/66 Primary Examiner-Norman G. Torchin Assistant Examiner-.ludson R. Hightower Attorney-Walter O. Hodsdon and Alfred P. Lorenzo [57] ABSTRACT 3 Claims, No Drawings NEUTRALIZING BATH FOR USE IN PHOTOGRAPHIC PROCESSING This invention relates in general to photography and in particular to an aqueous bath for use in processing photographic elements. More specifically, this invention relates to an aqueous neutralizing bath which is employed to neutralize residual aldehyde resulting from treatment of the photographic element with an aldehydic prehardening bath.

As disclosed in U.S. Pat. No. 3,168,400 to John Blackmer and Howard W. Vogt, an aqueous bath containing hydroxylamine or a water-soluble acid addition salt of hydroxylamine can be employed to treat photographic elements which have been hardened in an aldehydic prehardening bath for the purpose of neutralizing the residual aldehyde. By this means, hardening of the hydrophilic colloid to facilitate high-temperature processing can be achieved without the problems associated with carry through of the aldehyde into subsequent processing baths, such as color developers. However, the lack of stability of an aldehyde-neutralizing bath containing hydroxylamine, or its acid addition salts, is a serious problem which has hindered its commercial utilization. In particular, it has not been feasible to store the aqueous neutralizing bath for an adequate period of time because of decomposition of the hydroxylamine resulting in the formation of nitrogen and/or nitrogen oxides with consequent buildup of gas pressure which will eventually damage the container. The problem is particularly acute when the neutralizing bath is packaged as a concentrated solution, for example as a stock solution which is diluted with water at the time of use.

In accordance with this invention, the aforesaid problem is overcome, and an aldehyde-neutralizing bath of greatly improved stability if provided, by incorporating in the bath an hydroxyalkylidene diphosphonic acid or water-soluble salt thereof in an amount sufficient to inhibit the decomposition of the hydroxylamine. The resulting bath can be stored for long periods of time, such as periods of several months or more, even when it is prepared in a concentrated form.

More specifically, the novel neutralizing bath of the present invention comprises an aqueous solution of (l) hydroxylamine (H N-OH), or a water-soluble acid addition salt of hydroxylamine such as hydroxylamine sulfate, hydroxylamine hydrochloride, hydroxylamine phosphate, and the like, and (2) hydroxyalkylidene diphosphonic acid of the formula:

where R is a lower alkyl group, i.e., an alkyl group of one to five carbon atoms such as methyl, ethyl, propyl, isopropyl, nbutyl, n-pentyl, and the like, or a water-soluble salt of an hydroxyalkylidene diphosphonic acid of the above formula, such as an ammonium or alkali metal salt.

The hydroxyalkylidene diphosphonic acids of the above formula, and their water-soluble salts, are known compounds and are described, for example, in U.S. Pat. No. 3,214,454.

The hydroxylamine or water-soluble acid addition salt of hydroxylamine, may be present in the neutralizing bath in any suitable amount sufficient to neutralize the residual aldehyde. Amounts of from about 1 to about 100 grams per liter of solution are typically employed. The hydroxyalkylidene diphosphonic acid or water-soluble salt thereof may be empH control. As described in U.S. Pat. No. 3,168,400, good results are obtained with neutralizing baths with a pH in the range of from about 4.5 to about 8.0. An alkali metal bromide, such as sodium bromide, may be added for the purpose of maintaining the bromide level in the emulsion layers of the photographic element at the desired concentration, while sodium sulfate may be employed to aid in controlling swelling of the emulsion layers.

The manner in which the above-described hydroxyalkylidene diphosphonic acids or salts function to prevent decomposition of hydroxylamine is not known. These compounds are chelating agents for polyvalent metal ions and may function to complex trace amounts of heavy metal ions in the solution which could serve to catalyze the decomposition of hydroxylamine. However, other well-known chelating agents do not prevent the decomposition of hydroxylamine but, on the contrary, act to accelerate such decomposition as shown by the examples which follow.

The invention is further illustrated by the following examples. The neutralizing baths described in these examples are concentrated stock solutions which would ordinarily be diluted with water in an amount of about five times their volume prior to use in photographic processing.

EXAMPLE l An aldehyde-neutralizing bath, designated hereinafter as bath 1, was prepared in accordance with the following formulation:

Water 700 milliliters Hydroxylaminc sulfate 82.5 grams Glacial acetic acid 22.5 milliliters Sodium sulfate (anhydrous) I25 grams Sodium hydroxide (50% solution) 20.7 milliliters Sodium bromide 50 grams Water to one liter pH at F. 5.0

Bath 1 was divided into two equal portions and to one of these there was added, in an amount of 6 milliliters per liter, a 60 percent by weight aqueous solution of l-hydroxyethylidenel,l-diphosphonic acid of the formula:

Both portions were tested in a gas evolution apparatus which maintained a temperature of l25 F. and the volume of gas evolved was measured as a function of time. The apparatus consisted of a l,000-ml. round-bottom flask to which two 25- ml. burettes were joined, one burette being used to add the sample and the other having a U-tube on the end connected to a mercury reservoir so as to form a manometer. The test was continued for a period of 43 hours and at the end of this time the ratio of the total volume of gas evolved from the solution which contained l-hydroxyethylidene-l,l-diphosphonic acid EXAMPLE 2 An aldehyde-neutralizing bath, designated hereinafter as bath 2, was prepared using the same ingredients and proportions as employed for bath 1 of Example 1. Bath 2 was divided into two equal portions and to one of these there was added, in an amount of 6 milliliters per liter, a 60 percent by weight aqueous solution of pentasodium aminotri(methylphosphonate) of the formula N(CH,PO Na H. Both portions were tested in the gas evolution apparatus described in Example 1 for a period of 44 hours and at the end of this time the ratio of the total volume of gas evolved from the solution which contained pentasodium aminotri(methylphosphonate) to that evolved from the solu tion which did not contain pentasodium aminotri(methylphosphonate) was 2.1

EXAMPLE 3 An aldehyde-neutralizing bath, designated hereinafter as bath 3, was prepared using the same ingredients and proportions as employed for bath 1 of Example 1. Bath 3 was divided into two equal portions and to one of these there was added the disodium salt of ethylenediaminetetraacetic acid in an amount of 3 grams per liter. Both portions were tested in the gas evolution apparatus described in Example 1 for a period of l9 hours and at the end of this time the ratio of the total volume of gas evolved from the solution which contained the disodium salt of ethylenediaminetetraacetic acid to that evolved from the solution which did not contain the disodium salt of ethylenediaminetetraacetic acid was 7.7.

EXAMPLE 4 An aldehyde-neutralizing bath, designated hereinafter as bath 4, was prepared using the same ingredients and proportions as employed for bath 1 of Example 1. Bath 4 was divided into two equal portions, designated portion A and portion B. to portion A there was added, in an amount of 6 milliliters per liter, a 60 percent by weight aqueous solution of l-hydroxyethylidene-l,l-diphosphonic acid. To portion B there was added sodium hexametaphosphate in an amount of 3 grams per liter. Both portion A and portion B were tested in the gas evolution apparatus described in Example 1 for a period of 5 hours and at the end of this time the ratio of the total volume of gas evolved from portion A to that evolved from portion B was 0.05 3.

EXAMPLE 5 An aldehyde-neutralizing bath, designated hereinafter as bath 5, was prepared in accordance with the following formulation:

Water 700 milliliters Hydroxylamine sulfate 82.5 grams Glacial acetic acid 45 milliliters Sodium sulfate (anhydrous) 125 grams Sodium hydroxide (50% solution) 39.5 milliliters Sodium bromide 90 grams Water to 1 liter pH at 80 F. 5.l

Bath 5 was divided into two equal portions and to one of these there was added, in an amount of 6 milliliters per liter, a 60 percent by weight aqueous solution of l-hydroxyethylidenel,l-diphosphonic acid. Both portions were packaged in identical polyethylene containers and stored at a temperature of 120 F. After 3 weeks of storage, gas had evolved from the solution which did not contain l-hydroxyethylidene-l,ldiphosphonic acid to such an extent that damage to the container sufficient to cause leakage was imminent. On the other hand, the container with the solution stabilized with l-hydroxyethylidenel l -diphosphonic acid was in good condition after 2 months storage and the bath was still fully satisfactory for use in photographic processing. It is estimated that storage at 120 F. for 2 months is equivalent to 1 year at room temperature.

It is to be noted that while baths 1 through 4 were each prepared from the same proportions of the same chemicals, the amounts of metal contaminants present which could catalyze the decomposition'of hydroxylamine were not necessarily the same in each case, since the compounds used were commercially available products and these are never absolute] pure. Thus, baths 1 through 4 evolved gas at substantially di ferent rates. For this reason, comparison is made herein only with respect to a given bath so that it is only the effect of the presence of the chelating agent which is involved. Upon considering the examples given, it will be seen that use in Example 1 of l-hydroxyethylidene-l ,l-diphosphonic acid greatly reduced the amount of gas evolution as compared to the same neutralizing bath with no chelating agent. On the other hand, as shown by Examples 2 and 3, use of other commonly employed chelating agents caused a substantial increase in gas evolution. Example 4 compares the use of l-hydroxyethylidene-l,l-diphosphonic acid with the well-known chelating agent sodium hexametaphosphate and shows that gas evolution is only about one-twentieth as great with l-hydroxyethylidene-l,l-diphosphonic acid. Example 5 demonstrates that neutralizing baths containing an hydroxyalkylidene diphosphonic acid in accordance with this invention are sufficiently stable to be stored for long periods of time.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

lclaim:

1. A neutralizing bath for use in photographic processing comprising an aqueous solution of I) an aldehyde-neutralizing agent selected from the group consisting of hydroxylamine and water-soluble acid addition salts of hydroxylamine and (2) a hydroxyalkylidene diphosphonic acid of the formuia:

where R is a lower alkyl group, or a water-soluble salt of said hydroxyalkylidene diphosphonic acid, in an amount sufficient to inhibit the decomposition of said aldehyde-neutralizing agent.

2. A neutralizing bath as described in claim 1 wherein said aldehyde-neutralizing agent is present in an amount of about i to about grams per liter of solution and said hydroxyalkylidene diphosphonic acid or water-soluble salt thereof is present in an amount of about 0.5 to about 25 grams per liter of solution.

3. A neutralizing bath as described in claim 2 wherein said aldehyde-neutralizing agent is hydroxylamine sulfate and said hydroxyalkylidene diphosphonic acid is l-hydroxyethylidenel,l-diphosphonic acid. 

2. A neutralizing bath as described in claim 1 wherein said aldehyde-neutralizing agent is present in an amount of about 1 to about 100 grams per liter of solution and said hydroxyalkylidene diphosphonic acid or water-soluble salt thereof is present in an amount of about 0.5 to about 25 grams per liter of solution.
 3. A neutralizing bath as described in claim 2 wherein said aldehyde-neutralizing agent is hydroxylamine sulfate and said hydroxyalkylidene diphosphonic acid is 1-hydroxyethylidene-1,1-diphosphonic acid. 